Abstract

We report the field and angular dependences of of truly epitaxial Co-doped thin filmsgrown on with different template thicknesses. The films show comparable to single crystals and a maximum pinning force at indicative of strong high-field vortex pinning. Due to the strong correlated -axis pinning, for field along the -axis exceeds for plane, inverting the expectation of the anisotropy. High resolution transmission electron microscopy reveals that the strong vortex pinning is due to a high density of nanosize columnar defects.

Work at NHMFL was supported under NSF Cooperative Agreement No. DMR-0084173, by the State of Florida, and by AFOSR Grant No. FA9550-06-1-0474. Work at the University of Wisconsin was supported by funding from the DOE Office of Basic Energy Sciences under Award No. DE-FG02-06ER46327. TEM work at the University of Michigan was supported by the DOE Grant No. DE-FG02-07ER46416. TEM facility was supported by NSF.